I thought I'd put up a friendly reminder for those who know, or some useful information for those who don't: using children in your GraphQL will (by default) only return 10 items, however the children keyword in Sitecore GraphQL is in fact a function! With this information you can find that you can filter and paginate your list of child items.
While the vast majority of examples you find are something like this:
You can actually write it as:
There really don't seem to be that many examples around which use these features of children (though there are many showing similar parameters for search), so hope this helps someone!